r199513 - Fix string-literal to char* conversion in overload resolution for C++11

Chandler Carruth chandlerc at google.com
Fri Jan 24 00:55:01 PST 2014


Can we revert until a fix is ready? 7 days with msan failures is too many.


On Thu, Jan 23, 2014 at 8:08 PM, Richard Smith <metafoo at gmail.com> wrote:

> Looks like the msan build bot has found a bug here:
>
>
> http://lab.llvm.org:8011/builders/sanitizer-x86_64-linux-bootstrap/builds/1844/steps/annotate/logs/stdio
>
> It appears that some path through the code doesn't initialize Deprecated
> StringLiteralToCharPtr.
>
> On Fri Jan 17 2014 at 1:15:20 PM, Ismail Pazarbasi <
> ismail.pazarbasi at gmail.com> wrote:
>
> Author: ismailp
> Date: Fri Jan 17 15:08:52 2014
> New Revision: 199513
>
> URL: http://llvm.org/viewvc/llvm-project?rev=199513&view=rev
> Log:
> Fix string-literal to char* conversion in overload resolution for C++11
>
> String literal to char* conversion is deprecated in C++03, and is removed
> in
> C++11. We still accept this conversion in C++11 mode as an extension, if
> we find
> it in the best viable function.
>
>
> Modified:
>     cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td
>     cfe/trunk/lib/Sema/SemaExprCXX.cpp
>     cfe/trunk/lib/Sema/SemaOverload.cpp
>     cfe/trunk/test/SemaCXX/cxx0x-type-convert-construct.cpp
>     cfe/trunk/test/SemaCXX/deprecated.cpp
>     cfe/trunk/test/SemaCXX/overload-0x.cpp
>     cfe/trunk/unittests/ASTMatchers/ASTMatchersTest.cpp
>
> Modified: cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Basic/
> DiagnosticSemaKinds.td?rev=199513&r1=199512&r2=199513&view=diff
> ============================================================
> ==================
> --- cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td (original)
> +++ cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td Fri Jan 17
> 15:08:52 2014
> @@ -4534,6 +4534,9 @@ def ext_array_init_parens : ExtWarn<
>  def warn_deprecated_string_literal_conversion : Warning<
>    "conversion from string literal to %0 is deprecated">,
>    InGroup<CXX11CompatDeprecatedWritableStr>;
> +def ext_deprecated_string_literal_conversion : ExtWarn<
> +  "ISO C++11 does not allow conversion from string literal to %0">,
> +  InGroup<CXX11CompatDeprecatedWritableStr>, SFINAEFailure;
>  def warn_deprecated_string_literal_conversion_c : Warning<
>    "dummy warning to enable -fconst-strings">,
> InGroup<DeprecatedWritableStr>, DefaultIgnore;
>  def err_realimag_invalid_type : Error<"invalid type %0 to %1 operator">;
>
> Modified: cfe/trunk/lib/Sema/SemaExprCXX.cpp
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaE
> xprCXX.cpp?rev=199513&r1=199512&r2=199513&view=diff
> ============================================================
> ==================
> --- cfe/trunk/lib/Sema/SemaExprCXX.cpp (original)
> +++ cfe/trunk/lib/Sema/SemaExprCXX.cpp Fri Jan 17 15:08:52 2014
> @@ -3058,9 +3058,12 @@ Sema::PerformImplicitConversion(Expr *Fr
>                               CK_NoOp, VK, /*BasePath=*/0, CCK).take();
>
>      if (SCS.DeprecatedStringLiteralToCharPtr &&
> -        !getLangOpts().WritableStrings)
> -      Diag(From->getLocStart(), diag::warn_deprecated_string_l
> iteral_conversion)
> +        !getLangOpts().WritableStrings) {
> +      Diag(From->getLocStart(), getLangOpts().CPlusPlus11
> +           ? diag::ext_deprecated_string_literal_conversion
> +           : diag::warn_deprecated_string_literal_conversion)
>          << ToType.getNonReferenceType();
> +    }
>
>      break;
>    }
>
> Modified: cfe/trunk/lib/Sema/SemaOverload.cpp
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaO
> verload.cpp?rev=199513&r1=199512&r2=199513&view=diff
> ============================================================
> ==================
> --- cfe/trunk/lib/Sema/SemaOverload.cpp (original)
> +++ cfe/trunk/lib/Sema/SemaOverload.cpp Fri Jan 17 15:08:52 2014
> @@ -1443,7 +1443,6 @@ static bool IsStandardConversion(Sema &S
>
>    // Standard conversions (C++ [conv])
>    SCS.setAsIdentityConversion();
> -  SCS.DeprecatedStringLiteralToCharPtr = false;
>    SCS.IncompatibleObjC = false;
>    SCS.setFromType(FromType);
>    SCS.CopyConstructor = 0;
> @@ -1542,7 +1541,7 @@ static bool IsStandardConversion(Sema &S
>      FromType = S.Context.getArrayDecayedType(FromType);
>
>      if (S.IsStringLiteralToNonConstPointerConversion(From, ToType)) {
> -      // This conversion is deprecated. (C++ D.4).
> +      // This conversion is deprecated in C++03 (D.4)
>        SCS.DeprecatedStringLiteralToCharPtr = true;
>
>        // For the purpose of ranking in overload resolution
> @@ -3259,18 +3258,15 @@ Sema::DiagnoseMultipleUserDefinedConvers
>      IsUserDefinedConversion(*this, From, ToType, ICS.UserDefined,
>                              CandidateSet, false, false);
>    if (OvResult == OR_Ambiguous)
> -    Diag(From->getLocStart(),
> -         diag::err_typecheck_ambiguous_condition)
> -          << From->getType() << ToType << From->getSourceRange();
> +    Diag(From->getLocStart(), diag::err_typecheck_ambiguous_condition)
> +        << From->getType() << ToType << From->getSourceRange();
>    else if (OvResult == OR_No_Viable_Function && !CandidateSet.empty()) {
>      if (!RequireCompleteType(From->getLocStart(), ToType,
> -                          diag::err_typecheck_nonviable_condition_
> incomplete,
> +                             diag::err_typecheck_nonviable_
> condition_incomplete,
>                               From->getType(), From->getSourceRange()))
> -      Diag(From->getLocStart(),
> -           diag::err_typecheck_nonviable_condition)
> -           << From->getType() << From->getSourceRange() << ToType;
> -  }
> -  else
> +      Diag(From->getLocStart(), diag::err_typecheck_nonviable_condition)
> +          << From->getType() << From->getSourceRange() << ToType;
> +  } else
>      return false;
>    CandidateSet.NoteCandidates(*this, OCD_AllCandidates, From);
>    return true;
> @@ -3280,37 +3276,43 @@ Sema::DiagnoseMultipleUserDefinedConvers
>  /// of two user-defined conversion sequences to determine whether any
> ordering
>  /// is possible.
>  static ImplicitConversionSequence::CompareKind
> -compareConversionFunctions(Sema &S,
> -                           FunctionDecl *Function1,
> +compareConversionFunctions(Sema &S, FunctionDecl *Function1,
>                             FunctionDecl *Function2) {
>    if (!S.getLangOpts().ObjC1 || !S.getLangOpts().CPlusPlus11)
>      return ImplicitConversionSequence::Indistinguishable;
> -
> +
>    // Objective-C++:
>    //   If both conversion functions are implicitly-declared conversions
> from
> -  //   a lambda closure type to a function pointer and a block pointer,
> +  //   a lambda closure type to a function pointer and a block pointer,
>    //   respectively, always prefer the conversion to a function pointer,
>    //   because the function pointer is more lightweight and is more likely
>    //   to keep code working.
>    CXXConversionDecl *Conv1 = dyn_cast<CXXConversionDecl>(Function1);
>    if (!Conv1)
>      return ImplicitConversionSequence::Indistinguishable;
> -
> +
>    CXXConversionDecl *Conv2 = dyn_cast<CXXConversionDecl>(Function2);
>    if (!Conv2)
>      return ImplicitConversionSequence::Indistinguishable;
> -
> +
>    if (Conv1->getParent()->isLambda() && Conv2->getParent()->isLambda()) {
>      bool Block1 = Conv1->getConversionType()->isBlockPointerType();
>      bool Block2 = Conv2->getConversionType()->isBlockPointerType();
>      if (Block1 != Block2)
> -      return Block1? ImplicitConversionSequence::Worse
> -                   : ImplicitConversionSequence::Better;
> +      return Block1 ? ImplicitConversionSequence::Worse
> +                    : ImplicitConversionSequence::Better;
>    }
>
>    return ImplicitConversionSequence::Indistinguishable;
>  }
> -
> +
> +static bool hasDeprecatedStringLiteralToCharPtrConversion(
> +    const ImplicitConversionSequence &ICS) {
> +  return (ICS.isStandard() && ICS.Standard.DeprecatedStringLiteralToCharPtr)
> ||
> +         (ICS.isUserDefined() &&
> +          ICS.UserDefined.Before.DeprecatedStringLiteralToCharPtr);
> +}
> +
>  /// CompareImplicitConversionSequences - Compare two implicit
>  /// conversion sequences to determine whether one is better than the
>  /// other or if they are indistinguishable (C++ 13.3.3.2).
> @@ -3333,6 +3335,32 @@ CompareImplicitConversionSequences(Sema
>    //   described in 13.3.3.2, the ambiguous conversion sequence is
>    //   treated as a user-defined sequence that is indistinguishable
>    //   from any other user-defined conversion sequence.
> +
> +  // String literal to 'char *' conversion has been deprecated in C++03.
> It has
> +  // been removed from C++11. We still accept this conversion, if it
> happens at
> +  // the best viable function. Otherwise, this conversion is considered
> worse
> +  // than ellipsis conversion. Consider this as an extension; this is not
> in the
> +  // standard. For example:
> +  //
> +  // int &f(...);    // #1
> +  // void f(char*);  // #2
> +  // void g() { int &r = f("foo"); }
> +  //
> +  // In C++03, we pick #2 as the best viable function.
> +  // In C++11, we pick #1 as the best viable function, because ellipsis
> +  // conversion is better than string-literal to char* conversion (since
> there
> +  // is no such conversion in C++11). If there was no #1 at all or #1
> couldn't
> +  // convert arguments, #2 would be the best viable function in C++11.
> +  // If the best viable function has this conversion, a warning will be
> issued
> +  // in C++03, or an ExtWarn (+SFINAE failure) will be issued in C++11.
> +
> +  if (S.getLangOpts().CPlusPlus11 && !S.getLangOpts().WritableStrings &&
> +      hasDeprecatedStringLiteralToCharPtrConversion(ICS1) !=
> +      hasDeprecatedStringLiteralToCharPtrConversion(ICS2))
> +    return hasDeprecatedStringLiteralToCharPtrConversion(ICS1)
> +               ? ImplicitConversionSequence::Worse
> +               : ImplicitConversionSequence::Better;
> +
>    if (ICS1.getKindRank() < ICS2.getKindRank())
>      return ImplicitConversionSequence::Better;
>    if (ICS2.getKindRank() < ICS1.getKindRank())
> @@ -4244,6 +4272,7 @@ TryReferenceInit(Sema &S, Expr *Init, Qu
>        ICS.Standard.BindsImplicitObjectArgumentWithoutRefQualifier =
> false;
>        ICS.Standard.ObjCLifetimeConversionBinding =
> ObjCLifetimeConversion;
>        ICS.Standard.CopyConstructor = 0;
> +      ICS.Standard.DeprecatedStringLiteralToCharPtr = false;
>
>        // Nothing more to do: the inaccessibility/ambiguity check for
>        // derived-to-base conversions is suppressed when we're
> @@ -4318,6 +4347,7 @@ TryReferenceInit(Sema &S, Expr *Init, Qu
>      ICS.Standard.BindsImplicitObjectArgumentWithoutRefQualifier = false;
>      ICS.Standard.ObjCLifetimeConversionBinding = ObjCLifetimeConversion;
>      ICS.Standard.CopyConstructor = 0;
> +    ICS.Standard.DeprecatedStringLiteralToCharPtr = false;
>      return ICS;
>    }
>
>
> Modified: cfe/trunk/test/SemaCXX/cxx0x-type-convert-construct.cpp
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaCXX/
> cxx0x-type-convert-construct.cpp?rev=199513&r1=199512&r2=199513&view=diff
> ============================================================
> ==================
> --- cfe/trunk/test/SemaCXX/cxx0x-type-convert-construct.cpp (original)
> +++ cfe/trunk/test/SemaCXX/cxx0x-type-convert-construct.cpp Fri Jan 17
> 15:08:52 2014
> @@ -9,9 +9,9 @@ void f() {
>    Ustr = U"a UTF-32 string"; // expected-error {{assigning to 'char32_t
> *' from incompatible type 'const char32_t [16]'}}
>
>    char *Rstr;
> -  Rstr = R"foo(a raw string)foo"; // expected-warning{{conversion from
> string literal to 'char *' is deprecated}}
> +  Rstr = R"foo(a raw string)foo"; // expected-warning{{ISO C++11 does not
> allow conversion from string literal to 'char *'}}
>    wchar_t *LRstr;
> -  LRstr = LR"foo(a wide raw string)foo"; // expected-warning{{conversion
> from string literal to 'wchar_t *' is deprecated}}
> +  LRstr = LR"foo(a wide raw string)foo"; // expected-warning{{ISO C++11
> does not allow conversion from string literal to 'wchar_t *'}}
>    char *u8Rstr;
>    u8Rstr = u8R"foo(a UTF-8 raw string)foo"; // expected-error {{assigning
> to 'char *' from incompatible type 'const char [19]'}}
>    char16_t *uRstr;
>
> Modified: cfe/trunk/test/SemaCXX/deprecated.cpp
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaCXX/
> deprecated.cpp?rev=199513&r1=199512&r2=199513&view=diff
> ============================================================
> ==================
> --- cfe/trunk/test/SemaCXX/deprecated.cpp (original)
> +++ cfe/trunk/test/SemaCXX/deprecated.cpp Fri Jan 17 15:08:52 2014
> @@ -24,12 +24,15 @@ void stuff() {
>    register int m asm("rbx"); // no-warning
>
>    int k = to_int(n); // no-warning
> -
>    bool b;
>    ++b; // expected-warning {{incrementing expression of type bool is
> deprecated}}
>
> -  // FIXME: This is ill-formed in C++11.
> -  char *p = "foo"; // expected-warning {{conversion from string literal
> to 'char *' is deprecated}}
> +  char *p = "foo";
> +#if __cplusplus < 201103L
> +  // expected-warning at -2 {{conversion from string literal to 'char *' is
> deprecated}}
> +#else
> +  // expected-warning at -4 {{ISO C++11 does not allow conversion from
> string literal to 'char *'}}
> +#endif
>  }
>
>  struct S { int n; };
>
> Modified: cfe/trunk/test/SemaCXX/overload-0x.cpp
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaCXX/
> overload-0x.cpp?rev=199513&r1=199512&r2=199513&view=diff
> ============================================================
> ==================
> --- cfe/trunk/test/SemaCXX/overload-0x.cpp (original)
> +++ cfe/trunk/test/SemaCXX/overload-0x.cpp Fri Jan 17 15:08:52 2014
> @@ -1,7 +1,11 @@
> -// RUN: %clang_cc1 -fsyntax-only -std=c++11 -verify %s
> +// RUN: %clang_cc1 -fsyntax-only -std=c++11 -verify %s
> +// RUN: %clang_cc1 -fsyntax-only -verify %s
>
>  namespace test0 {
> -  struct A { // expected-note {{candidate function (the implicit copy
> assignment operator) not viable: 'this' argument has type 'const test0::A',
> but method is not marked const}} expected-note {{candidate function (the
> implicit move assignment operator) not viable: 'this' argument has type
> 'const test0::A', but method is not marked const}}
> +  struct A { // expected-note {{candidate function (the implicit copy
> assignment operator) not viable: 'this' argument has type 'const test0::A',
> but method is not marked const}}
> +#if __cplusplus >= 201103L
> +  // expected-note at -2 {{candidate function (the implicit move assignment
> operator) not viable: 'this' argument has type 'const test0::A', but method
> is not marked const}}
> +#endif
>      A &operator=(void*); // expected-note {{candidate function not
> viable: 'this' argument has type 'const test0::A', but method is not marked
> const}}
>    };
>
> @@ -9,3 +13,79 @@ namespace test0 {
>      a = "help"; // expected-error {{no viable overloaded '='}}
>    }
>  }
> +
> +namespace PR16314 {
> +  void f(char*);
> +  int &f(...);
> +  void x()
> +  {
> +    int &n = f("foo");
> +#if __cplusplus < 201103L
> +    // expected-warning at -2 {{conversion from string literal to 'char *'
> is deprecated}}
> +    // expected-error at -3 {{non-const lvalue reference to type 'int'
> cannot bind to a temporary of type 'void'}}
> +#endif
> +  }
> +}
> +
> +namespace warn_if_best {
> +  int f(char *);
> +  void f(double);
> +  void x()
> +  {
> +    int n = f("foo");
> +#if __cplusplus < 201103L
> +    // expected-warning at -2 {{conversion from string literal to 'char *'
> is deprecated}}
> +#else
> +    // expected-warning at -4 {{ISO C++11 does not allow conversion from
> string literal to 'char *'}}
> +#endif
> +  }
> +}
> +
> +namespace userdefined_vs_illformed {
> +  struct X { X(const char *); };
> +
> +  void *f(char *p); // best for C++03
> +  double f(X x);  // best for C++11
> +  void g()
> +  {
> +    double d = f("foo");
> +#if __cplusplus < 201103L
> +    // expected-warning at -2 {{conversion from string literal to 'char *'
> is deprecated}}
> +    // expected-error at -3 {{cannot initialize a variable of type 'double'
> with an rvalue of type 'void *'}}
> +#endif
> +  }
> +}
> +
> +namespace sfinae_test {
> +  int f(int, char*);
> +
> +  template<int T>
> +  struct S { typedef int type; };
> +
> +  template<>
> +  struct S<sizeof(int)> { typedef void type; };
> +
> +  // C++11: SFINAE failure
> +  // C++03: ok
> +  template<typename T> int cxx11_ignored(T, typename S<sizeof(f(T(),
> "foo"))>::type *);
> +#if __cplusplus < 201103L
> +  // expected-warning at -2 {{conversion from string literal to 'char *' is
> deprecated}}
> +#else
> +  // expected-note at -4 {{candidate template ignored: substitution
> failure}}
> +#endif
> +
> +  // C++11: better than latter
> +  // C++03: worse than latter
> +  template<typename T> void g(T, ...);
> +  template<typename T> int g(T, typename S<sizeof(f(T(), "foo"))>::type
> *);
> +#if __cplusplus < 201103L
> +  // expected-warning at -2 {{conversion from string literal to 'char *' is
> deprecated}}
> +#endif
> +
> +  int a = cxx11_ignored(0, 0);
> +  int b = g(0, 0);
> +#if __cplusplus >= 201103L
> +  // expected-error at -3 {{no matching function for call to
> 'cxx11_ignored'}}
> +  // expected-error at -3 {{cannot initialize a variable of type 'int' with
> an rvalue of type 'void'}}
> +#endif
> +}
>
> Modified: cfe/trunk/unittests/ASTMatchers/ASTMatchersTest.cpp
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/unittests/ASTM
> atchers/ASTMatchersTest.cpp?rev=199513&r1=199512&r2=199513&view=diff
> ============================================================
> ==================
> --- cfe/trunk/unittests/ASTMatchers/ASTMatchersTest.cpp (original)
> +++ cfe/trunk/unittests/ASTMatchers/ASTMatchersTest.cpp Fri Jan 17
> 15:08:52 2014
> @@ -2608,13 +2608,13 @@ TEST(ReinterpretCast, DoesNotMatchOtherC
>  }
>
>  TEST(FunctionalCast, MatchesSimpleCase) {
> -  std::string foo_class = "class Foo { public: Foo(char*); };";
> +  std::string foo_class = "class Foo { public: Foo(const char*); };";
>    EXPECT_TRUE(matches(foo_class + "void r() { Foo f = Foo(\"hello
> world\"); }",
>                        functionalCastExpr()));
>  }
>
>  TEST(FunctionalCast, DoesNotMatchOtherCasts) {
> -  std::string FooClass = "class Foo { public: Foo(char*); };";
> +  std::string FooClass = "class Foo { public: Foo(const char*); };";
>    EXPECT_TRUE(
>        notMatches(FooClass + "void r() { Foo f = (Foo) \"hello world\"; }",
>                   functionalCastExpr()));
>
>
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